In the fabrication of integrated circuitry, electronic devices at different elevations within a substrate often need to be electrically connected. One manner of doing so includes initially fabricating a device at one elevation, depositing an insulative material thereover, and etching a contact opening through the insulative material to a desired point of electrical contact of the electronic device. The opening is then filled with conductive material, and the higher elevation device is fabricated over and in electrical connection with the conductive material which has filled the opening. Alternately, another insulative layer may be deposited over the plugged opening, and an opening etched therethrough which is targeted to overlie the conductive material filling the opening in the lower insulative material.
As integrated circuitry has continued to get denser by closer horizontal placement of individual electronic components relative to one another horizontally, the integration density has also tended to increase vertically. Such has led to thicker insulating layers through which contact openings are etched to access underlying electronic devices. A property of any opening to be etched is “aspect ratio”, which may be defined as the ratio of the maximum depth of the opening to be etched divided by the minimum lateral opening width of an outermost portion of the opening. It is generally more difficult to etch high aspect ratio openings in comparison to low aspect ratio openings. Further, the larger the outermost/uppermost area of the conductive material of a filled contact opening, the greater the misalignment margin in fabrication and/or use of a mask which is intended to provide an opening through material to such conductive outermost surface.
While the invention was motivated in addressing the above issues, and particularly in the fabrication of contact openings in Dynamic Random Access Memory (DRAM) circuitry, the invention is in no way so limited.